Fatty amine salts of alkyl phosphoric acids



Patented Oct. 23, 1945 FATTY AMINE SALTS OF ALKYL PHOSPHORIC ACIDSHerschel G. Smith, Wallingford, and Troy L. Gantrell, Lansdowne. Pa...assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation ofPennsylvania No Drawing. Application March 19, 1945, Serial No. 583,650

9 Claims. ('01. 260461) This invention relates to fatty amine salts ofalkyl phosphoric acids and it comprises oil-so1uble, substantiallyneutral addition products of 3-methyl-butyl, 2-ethyl-hexyl acidphosphate and a primary fatty amine containing from 8 to 18 carbonatoms, said neutral addition products being useful as rust preventivecompounds or rust inhibitors; and it further comprises methods of makingsaid neutral addition products wherein the said acid phosphate andprimary fatty amines are chemically combined together in approximatelyequimolecular ratios to produce substantially neutral addition productshaving a pH between 5.5 and 7.5. said addition products or amine saltsbeing readily soluble in and miscible with hydrocarbons such as volatilehydrocarbon solvents, mineral oils. waxes and the like; all as morefully hereinafter described and claimed.

This application is a continuation-in-part of our prior copendingapplication Serial No. 420.438, filed November 25, 1941. which became U.S. Patent No. 2,371,851 on March 20, 1945. In that application, we havedescribed and claimed improved anti-rust petroleum lubricants andmineral oil compositions containing minor amounts of the substantiallyneutral addition products of 3-methyl-butyl, 2-ethyl-hexyl acidphosphate and primary fatty amines containing 8 to 18 carbon atoms, as arust inhibitor or rust preventive compound. The present applicationisdirected to such rust inhibitors or rust preventive compounds, per se.

That is, the present invention relates to new oil-soluble, substantiallyneutral primary fatty amine salts of 3-methyl-butyl, 2-ethyl-hexylphosphoric acid. Generically, these fatty amine salts may be representedby the following formula:

wherein R represents an alkyl group containing from 8 to 18 carbonatoms. As shown by the above generic formula, these fatty amine saltsare addition products of 3-methyI-butyl, 2-ethyl-hexyl acid phosphatedi-ester and primary fatty amines containing from 8 to 18 carbon atoms.

As a class, these fatty amine salts are relatively non-volatile, even atelevated temperatures. Most of them are oily, viscous liquids at roomtemperatures. Others are soft, waxy solids which melt to oily liquids atslightly elevated temperatures. All of them are insoluble in water andaqueous liquids, and are resistant to hydrolysis. Indeed, these oily andwaxy amine salts are quite water-repellent. Also, they are relativelystable compounds. For instance, they can be heated to elevatedtemperatures as stated ante, and this is frequently done inincorporating them in waxes, petrolatums, and mineral oils. However, ifheated to excessive temperatures, say 260 F. or above, for long periods,they become converted into corresponding amide compounds, water beingsplit ofi at such higher temperatures.

Further, our new fatty amine salts are readily soluble in oils, bothmineral oils and fatty oils. Of course, their solubility varies somewhatwith the particular oil and amine salt, but is quite high in general.Further, in addition to being readily soluble in mineral oils, they arereadily miscible with other hydrocarbons, such as petrolatums, waxes andvolatile hydrocarbon liquids, and coating compositions containing thesame; they being readily soluble in hydrocarbon liquids, particularlyvolatile hydrocarbon solvents. When incorporated in hydrocarbons, suchas mineral oils and the like, they impart marked anti-rust qualitiesthereto, as shown in our prior application Serial No. 420,438, new U. S.Patent No. 2,371,851. In other words, as described and illustrated inthat application, our new primary fatty amine salts are excellent rustpreventive compounds or rust inhibitors.

Further, as described in our prior application Serial No. 420,438, nowU. S. Patent No. 2,371,851, our rust inhibitors or neutral additionproducts can be readily prepared by reacting 3-methylbutyl,2-ethyl-hexyl acid phosphate with the primary fatty amine inapproximately equimolecular ratios; the reaction being 50 controlled asto produce substantially neutral addition products having a pH valuewithin the range of 5.5 to 7.5 (as measured with a quinhydronecalomelelectrode assembly).

The above acid phosphate ester is a di-ester of ortho phosphoric acidand has the following formula:

This compound is also known as 3-methyl-butyl, 2-ethyl-hexyl orthophosphoric acid.

The primary fatty amines employed to react with the acid phosphate estermay be represented v by the following generic formula:

H2N-CH2-(CH2) nCHa wherein n is a number between 8 and 16. This genericclass includes the following members:

.We may prepare our rust inhibitors by reacting the acid phosphate esterwith some particular one of these amines, but more usually mixtures ofamines of this group are employed, as they afford a somewhat betterproduct than if only one amine is used. One commercially availablemixture which we ordinarily employ is so-called coco amine, made inknown ways by conversion of cocoanut oil fatty acids into thecorresponding amines. Coco amine contains a major amount of mon-laurylamine (the C12 amine) with minor amounts of its adjacent homologues. Thecommercial coco amine has an average molecular weight of 210, and thisvalue is taken as a commercial weight in reacting this commercial aminewith the said acid phosphate ester.

Generically, these primary fatty amines readily react with3-methyl-butyl, 2-ethyl-hexyl ortho phosphoric acid; the reaction beingquite exothermic, as shown in our prior application Serial No. 420,438,now U. S. Patent No. 2,371,851. As there stated, in making our rustinhibitors from these reagents, the reaction temperature is carefullycontrolled. Usually, the reaction temperature is held between 140 and200 F.; the reaction mixture being externally cooled if necessary.

The following examples illustrate certain advantageous embodiments ofthis invention:

Example I.Into a suitable vessel, equipped with means for heating,cooling and agitating the charge, there were charged 281 pounds of 3-methyl-butyl, 2-ethyl-hexyl ortho phosphoric acid, and then 185 poundsof dodecyl amine were gradually added; the said amine being added atsuch a rate as to maintain the temperature of the reaction mixture below180 F. and thus avoid splitting out water from the addition product soobtained. After the exothermic reaction had subsided, a further 18pounds of dodecyl amine were added and the reaction mixture stirreduntil the reaction was completed.

The amine salt or addition product so obtained was an oily, viscousliquid at room temperature. It had a light amber red color and apleasant odor. It was readily soluble in liquid hydrocarbons such asmineral oils, volatile hydrocarbon solvents and the like. Also, it wasreadily miscible with petrolatum, waxes and like hydrocarbons.

This dodecyl amine salt is an addition product having the followingformula:

ethyl-hexyl acid phosphate di-ester.

In the above example, in lieu of mono-lauryl amine (primary dodecylamine), other primary fatty amines may be employed to form similaroil-soluble neutral amine salts. For instance, mono-capryl amine,mono-stearyl amine, and the other primary fatty amines mentioned antemay be employed. As shown in our prior application Serial No. 420,438,now U. 5. Patent No. 2,371,851, all of these amine salts or additionproducts are excellent rust inhibitors.

Further, in the practice of this invention, mixtures of such primaryamines may be er ployed in forming our rust inhibitors. Indeed,sometimes commercial mixtures of these primary fatty amines are reactedwith the said acid phosphate di-esters to produce mixtures of theseamine salts or rust inhibitors, they being advantageous for the presentpurposes. The preparation of one such advantageous rust inhibitor orrust preventive compound is illustrated in the following example.

Example II.Into a suitable vessel, equipped with heating and coolingcoils and means for mechanical agitation, are added 210 pounds of cocoamine, and 281 pounds of 3-methyl-butyl, 2-ethyl-hexyl acid phosphateare slowly added so as to keep the temperature of the reaction below F.,whereby to avoid splitting out of of water from the addition product soformed. After the addition of the acid phosphate, a further 20 pounds ofcoco amine were added and the mixture stirred until the reaction wascompleted; about one hour being required. The addition products soobtained were substantially neutral amine salts; the pH value thereofbeing approximately 7.2.

Further, the product obtained in Example II was an oily, viscous liquidat room temperature. It had a light amber red color and a pleasant odor.It was readily soluble in mineral oils and light hydrocarbons, butpractically insoluble in water.

As the addition products obtained in the foregoing examples aresubstantially insoluble in water, the following procedure was used inmeasuring the pH of these amine salts and oils containing them. A samplethereof was dissolved in normal butanol containing a small amount ofwater and adjusted exactly to pH 7.0; the butanol dissolved thewater-insoluble amine salt and served as a blending agent for the water,but not appreciably altering-the pH value thereof. Then, the pH of thesample was measured by electrometric or colorimetric procedures; theresults obtained by either procedure being within the experimental errorof 'such procedures. That is, the pH is measured as described in ourprior application Serial No, 420,438, now U. S. Patent No. 2,371,851.

Further, as described in the application, the rust inhibitors soprepared may be incorporated in mineral oils to impart marked anti-rustqualities thereto; usually from 0.1 to 25% by weight on the oil beingemployed. That is, our rust inhibitors are readily soluble in mineraloils. In fact, they may be formed in situ in the mineral oil, asdescribed in our prior application Serial No. 420,438, nowU. S. PatentNo. 2,371,851; both the amine and acid phosphate di-ester beingthemselves readily soluble in the oils. Thus, in the practice of thepresent invention, mineral oils may be employed in Examples I and IIante as a solvent and diluent. Likewise, other hydrocarbons may be alsoemployed as a diluent in such methods, advantageously a volatilehydrocarbon solvent, such as solvent naphtha, Stoddard solvent, and thelike. The solutions in volatile solvent so obtained are useful informing protective coatings on metals; the evaporation of the solventcoating the metal with a water-resistant him of these rust inhibitors.In this way, metals can be ob fectively protected against rust andcorrosion I even when subjected to drastic conditions.

Likewise, our new amine salts or rust inhibitors are also soluble inother hydrocarbons, such as waxes, petrolatum, and the like. Thus,

. they can be readily incorporated in various coating compositions suchas heavy mineral oils,

greases, petrolatinn, petrolatum jellies, and.

waxes, as stated in our prior application Serial No. 420,438, new U. 8.Patent No. 2,371,851;

they being soluble in and compatible with such compositions. Whenincorporated therein, even in small amounts, they impart markedanti-rust qualities to such compositions.

Thus, a wide range of improved protective coating compositions may beprepared with the aid of our new rust inhibitors. Further, as statedante.

they are useful, per se. as rust preventive compounds.

What we claim is:

1. As new compositions of matter, useful as rust preventive compoundsand for other purposes, the oil-soluble addition salts having thefollowing formula:

n n n o n n 3. The composition of claim 1 wherein said addition salt isthe cocoamine salt of 3-methylbutyl, methyl-heal phosphoric acid. Y

4. As new compositions of matter, the oil-soluble addition salts ofs-methyl-butyl, :2-ethylhexyl phosphoric acid and primary fatty aminescontaining 8 to 18 carbon atoms, said amine salts being substantiallyneutral compounds soluble in mineral oils and miscible withhydrocarbons.

5. As an improvement in the manufacture of oil-soluble rust preventivecompounds, "the improved process which comprises reacting 3-methyl-butyl, z-ethyl-hexyl phosphoric acid and a primary fatty aminecontaining 8 to 18 carbon atoms, in substantially equimolecularproportions, while maintaining the reaction temperature below 200 F., toproduce substantiallyneutral addition products thereof.

6. The process of claim 5 wherein the reaction is effected attemperature between 140 and 200' I".

7. The process of claim 5 wherein the said reaction is effected in thepresence of a liquid hydrocarbon solvent, said solvent serving as adiluent to facilitate control of the reaction and the

